Abstract : The electric glow discharge in oxygen was experimentally studied and mathematically modeled for the parameter space of one to ten torr of pressure and for current densities up to 35 milliamperes per square centimeter. Experimentally it was observed that the oxygen discharge existed in one of two forms: a high-electric-field form or a low electric-field form. The high field form was present at high currents and low pressures, the low field form at low currents and high pressures. The high field form exhibited stable characteristics while the low field form was observed to be nonstable, exhibiting periodic or aperiodic oscillatory behavior. The periodic oscillations existed only at certain frequencies or modes, and the discharge impedance was a function of the frequency. The optical output of the oscillatory form of the discharge was highly modulated with short duty cycle pulses. The oscillations exhibited a small amount of normal disposition. The point of transition between forms and the electrical impedance of the forms was unaffected by the addition of an inert gas, argon, to the discharge. Adding an electron-detaching gas, carbon monoxide, increased the low field impedance until the difference between the forms essentially ceased to exist. Mass spectra measurements indicated that the atomic oxygen density increased significantly when the discharge transitioned from the low to high field forms. Solutions of the Boltzmann transport equation indicated that the electron energy distribution function exhibited a characteristic intermediate between Maxwellian and Druyvesteyn.